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| Titel |
Determination of triple oxygen isotope composition of tropospheric CO2 |
| VerfasserIn |
Sasadhar Mahata, Mao-Chang Liang, Chung-Ho Wang |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050192
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| Zusammenfassung |
| The isotopic composition of carbon dioxide originating at the surface is modified in
the stratosphere. Given that the only source of oxygen anomaly (Δ17O = δ17O –
0.516Ãδ18O > 0) is in the stratosphere, such isotopic signal provides a powerful
tracer for studying biogeochemical cycles involving carbon dioxide. In addition to
the exiting fluorination method that can achieve a precision as high as ~0.1 per
mil, we improved a previously proposed technique, CeO2 + CO2 equilibrium at
high temperature, to a precision of ~0.13 per mil and better. Such improvement
allows us monitor the changes of biogeochemical CO2 in detail. We successfully
measure Δ17O in near surface carbon dioxide. The temporal variation of Δ17O is
apparent. In addition, a 3-D numerical model that includes the isotopic fractionation
in the atmosphere has been developed. In this model we assume the biological
processes produce neutral Δ17O, i.e., mass-dependent CO2. Processes that affect
Δ17O in the troposphere are (1) chemistry in the atmosphere (mainly CO2 + O(1D)
isotope exchange), (2) large circulation that brings the isotopically heavy CO2 to
near the surface, and (3) biological processes that “reset” the isotopic composition.
Implications for constraining the sources and sinks of CO2 using its isotope signature are
discussed
References
[1] Assonov, S.S. and C.A.M. Brenninkmeijer, Rapid Communications in Mass
Spectrometry, 2001. 15: p.2426-2437
[2] Hofmann M. E.G. and A. Pack, Anal. Chem., 2010. 82(11):p. 4357-4361
[3] Liang, M. C., J. Tang., C. Y. Chan, X. D. Zeng and Y. L. Yung (2008), Geophys. Res.
Lett, 35, L20816, doi: 10.1029/2008GL035246
[4] Hoag, K. J., C. J. Still, I. Y. Fung, and K. A. Boering (2005), Geophys. Res. Lett, 32,
L02802, doi: 10.1029/2004GL021011 |
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